1. Field of the Invention
The present invention relates to a disc brake, and more particularly, to an electromechanical brake device capable of solving a structural problem that can occur at a piston unit or a brake device itself when a motor malfunctions.
2. Discussion of Related Art
In general, as brake devices are mounted on motor vehicle wheels, the braking force is obtained by operating a brake pedal while driving, and the braking force is generated by operating a parking brake lever so as to maintain a stop state while parking.
In the conventional brake device, as friction pads are provided on both sides of a disc, and a piston, which is driven by a hydraulic or a motor, strongly presses the friction pads to the disc, the motor vehicle is braked.
As an example, the conventional electromechanical brake device includes the disc and the friction pads described above, a motor, that is, a piston drive unit for pressing the friction pads to the disc, a decelerator connected to the motor, and a linear motion converting mechanism.
While the electromechanical brake device has a simple structure compared to that of the hydraulic brake device, it causes severe problems that the piston unit which is a main component and the linear motion converting mechanism configured to move the piston unit are overloaded when a rotational direction of the motor and the motor are malfunctioned.